Abstract : A photographic technique was developed using very narrow bandpass filters to record selective emission by magnesium and sodium, thus providing a means of mapping the location of these emissions in me. The relation between the flames of stoichiometric and fuel-rich compositions was further investigated, to compare the illuminance produced by the entire flame with that of a very small central area. A basic problem proved to be the difficulty of defining the effective area of the flame in a meaningful way, because of the influence of the spectral sensitivity of the film on the apparent area. The relative size of flames of similar spectral distribution, from NaNO3/Mg compositions, was studied with a special extended range film and the location of regions of maximum luminance determined at pressures of 760, 630, 150, 30 and 6 torr. No outstanding differences were observed in these spectra from different points in the flame. (Author)